Leading article: The risks of brinkmanship with Tehran

Now the Europeans are urging the UN nuclear watchdog to report Iran to the Security Council, which might mean sanctions, while Iran is upping the ante. In his latest broadside, the hard-line President Mahmoud Ahmadinejad warns Iran may continue producing enriched uranium, the material used to produce atomic reactor fuel or bomb-grade material.

The EU's delicate diplomatic game with Iran over nuclear weapons - drawn up in direct contrast with America's more belligerent approach - has been coming unstuck for some time. Some might say it has been ailing since the ink dried on last November's Paris agreement, when Iran reiterated that it would not seek to acquire nuclear weapons. From the start, Iran insisted that the agreement did not rule out continuing to develop nuclear power for peaceful purposes, an interpretation the Europeans disputed.

What upset Europe's equilibrium still more was the presidential election this June, which saw the unpredictable and unfriendly Mr Ahmadinejad accede to power. Since then Europe has been struggling to keep alive a relationship designed to suit a very different Iranian leadership from the one we confront.

If some fear we are stumbling down the same path of confrontation that led to war in Iraq, they are right to be worried, not least because the same elements in the US that always opposed Europe's peaceful engagement with Iran are still hungry to use "big stick" diplomacy.

For that reason, we need to be very aware of whatever ground our government chooses to take if it abandons the policy of constructive engagement with Iran. We need especially to remember that we derive our authority when dealing with Iran's nuclear ambitions from the 1968 Non-Proliferation Treaty, which not only limited the right of countries to acquire nuclear weapons but bound states in possession of such weapons to work to get rid of them. As anyone knows, either in London or Teheran, the West has applied a great deal of pressure to ensure the first part of the equation but there has been no similar movement towards fulfilling the latter part.

In these dangerous days we should beware of any attempt to bamboozle the public into thinking we enjoy heavenly authorisation to thwart Iran's nuclear ambitions by force. For the main lesson to be learned from the Iraq disaster is that we need to proceed cautiously and pragmatically in these complex disputes, and at all costs avoid being shoehorned into a conflict that we cannot then see our way out of.